International Food Research Journal 27(6): 1057- 1066 (December 2020) Journal homepage: http://www.ifrj.upm.edu.my Persimmon (Diospyros kaki Thunb.) seed: a potential nutritional source with antioxidant and pharmaceutical activity 1Han, C. H., 2Kim, I. D., 3Kwon, S. I., 4Dhungana, S. K., 1Jang, S. Y., 1Kim, M. J. and 1*Shin, D. H. 1School of Applied Biosciences, Kyungpook National University, Daegu 41566, Korea 2International Institute of Agricultural Research and Development, Kyungpook National University, Daegu 41566, Korea 3Department of Clinical Pathology, Daegu Health College, Daegu 41453, Korea 4National Institute of Crop Science, Rural Development Administration, Miryang 50424, Korea Article history Abstract Received: 13 July 2019 Pulp is a major part of persimmon fruit, for which it is widely cultivated in different parts of Received in revised form: the world. Persimmon seeds are generally discarded as waste. The objective of the present 4 March 2020 work was to investigate the nutritional, antioxidative, and pharmacological properties of the Accepted: 18 August 2020 seeds of three persimmon cultivars namely Jinyeong (JYS), Yangyangdongchulsi (YYS), and Hamanmulgam (HAS). JYS (9417.87 mg.kg-1) contained the highest concentration of total minerals, followed by HAS and YYS. The concentration of total organic acids was also the Keywords highest in JYS (5362.43 mg.kg-1), while the lowest in HAS (4411.1 mg.kg-1). Similarly, JYS antioxidant, and YYS contained the highest and lowest concentrations of free sugars, respectively. On the free radical scavenger, other hand, the total free amino acid contents were the highest in YYS (336.34 mg.100 g-1) nutrition, among the cultivars. The persimmon seeds also have good potential for scavenging free nutraceutical, radicals and inhibiting acetylcholinesterase activity. The seeds could also be considered to be persimmon seed a source of a therapeutic agent against Alzheimer’s disease, as the seed extract showed prom- ising anti-acetylcholinesterase activity. The overall results of the present work provide an insight into persimmon seeds, a by-product of persimmon fruit, as a potential product in the pharmaceutical and food industries. © All Rights Reserved Introduction reducing antioxidant potential than that of the pulp (Guo et al., 2003). Fruit pulp is a major part of persimmon (Dio- Reactive oxygen species (ROSs) are generated spyros kaki Thunb.), for which it is cultivated in many in living organisms as a result of normal cellular metab- parts of the world, especially in Korea, China, and olism, and are not harmful at moderate concentrations; Japan. The fruits are consumed raw, or subjected to however, at high concentrations, they produce adverse drying for preservation. Persimmon fruits are rich in modifications to cell components such as lipids, nutrients and phytochemicals, which account for their proteins, and DNA (Marnett, 1999). An imbalance high antioxidant, anti-infection, anti-inflammatory, between an oxidant and antioxidant in favour of the and antihemorrhagic properties (Kim et al., 2006). former, known as oxidative stress, is responsible for Persimmon seeds, which are generally discarded as many health problems including cancers, neurological by-products of persimmon also possess different disorders (Sayre et al., 2001), and hypertension (Kerr antioxidants as do many other fruits’ seeds such as et al., 1999). Antioxidants are of significant importance rambutan, mango, tamarind, and berry (Maisuthisakul in the prevention and treatment of several cellular et al., 2007). Persimmon seeds show a strong radical degenerations by blocking the initiation or propagation scavenging potential in vitro, and inhibit lipid peroxida- of oxidising chain reactions and consequently inhibit- tion in vivo (Ahn et al., 2002). Interestingly, seed and ing or delaying the oxidation process (Behera et al., calyx extracts of persimmon have significantly higher 2006). The antioxidants interfere with the production antioxidant activity and phenolic content than the fruit and the activation of free radicals, which protect the peel and flesh extracts, which results in a high protective human body from chronic diseases. Because the use effect against oxidative DNA damage (Jang et al., of synthetic antioxidants such as butylated hydroxyan- 2010). The seeds have more than ten times higher ferric isole, butylated hydroxytoluene, and propyl gallate has *Corresponding author. Email: [email protected] 1058 Han, C. H., et al./IFRJ 27(6) : 1057 - 1066 been questioned, and a negative perception of taking Victoria, Australia) was used to analyse the heavy such antioxidants has developed among consumers metals following a method described earlier due to long-term safety concerns, the demand for natu- (Gonzálvez et al., 2010). The concentration of mineral ral antioxidants has increased (Yu et al., 2002). elements was determined after calibration of the instru- Acetylcholinesterase (AChE) is a vital ments with the respective standard elements. enzyme in the nervous system that checks nerve impulses by proper hydrolysis of a neurotransmitter, Determination of organic acid contents acetylcholine. AChE inhibitors are of significant The concentration of organic acids was meas- importance for controlling several neurological prob- ured using high-performance liquid chromatography lems, and are accepted as the major drug for the treat- (HPLC) following the procedure reported by Ergönül ment of Alzheimer’s disease. and Nergiz (2010) with some modifications. Ten Although there are few reports on the antioxi- grams of seed powder was extracted with 10 mL of a dant potential of persimmon seeds, little work has been water/methanol solution (75:25, v/v) at room tempera- done to investigate the nutritional and pharmacologi- ture, and centrifuged (1,850 g, 30 min). One millilitre cal properties of persimmon seeds of different culti- of the sample extract was added to 9 mL of distilled vars. A collaborative research concluded that persim- water, kept overnight at room temperature, and filtered mon seeds have the potential to enhance the acceptance through a 0.22 µm syringe filter (Millipore, Billerica, of green tea (Kim et al., 2017). In a previous study, MA, USA). Conditions for the HPLC were: detector we investigated the biochemical constituents and (M996, Waters, Milford, MA, USA); refractive index antioxidant potential of persimmon seeds of four culti- detector (RI410, Waters); mobile phase, 0.005 mol.L-1 vars: Sangju Doongsi, Gyoungsan Bansi, Jinan H2SO4 in water; column (PL Hi-Plex H, 300 × 7.7 mm, Galgam, and Sanggam Doongsi (Bilal et al., 2016). Agilent Technologies, Seoul, Korea); column temper- Previous studies (Ahn et al., 2002; Jang et al., 2010; ature, 65°C; flow rate, 0.6 mL.min-1; and injection Bilal et al., 2016) have focused on the antioxidant volume, 10 µL. potentials of persimmon seeds. The objective of the present work was therefore to further investigate the Determination of free sugar contents nutritional and antioxidant potentials of the seeds of The free sugar content was examined by three other persimmon cultivars. following the method described by Génard and Souty (1996). Five grams of sample powder was mixed with Materials and methods 10 mL of distilled water, homogenised using a homog- enizer (Ultra-Turrax T-25, IKA-Lobortechnik, Seed materials Staufen, Germany), and followed by the addition of Persimmon seeds of three cultivars, namely 20 mL of distilled water and centrifugation (16,000 g, Jinyeong (JYS), Yangyangdongchulsi (YYS), and 30 min). The supernatant was filtered through a Hamanmulgam (HAS) were collected from Persim- Sep-Pak C18 cartridge (WAT023501, Waters) and a mon Experiment Station, Sangju, Korea. The three Millipore 0.45-syringe filter (PVDF, Whatman, cultivars are among the widely cultivated persimmon Tokyo, Japan). The quantification of free sugars was cultivars in Korea. At least ten fruits were harvested performed by HPLC (Model 9300, Young Lin, Gyeo- from ten plants of each cultivar at the ready-to-harvest nggi-do, Korea) under the following conditions: a stage. The seeds were collected from the fruits, column heater set at 85°C, sugar-pak (6.5 × 300 mm, thoroughly rinsed with tap water, and allowed to Alltech, Atlanta, GA, USA), and a mobile phase of -1 surface dry at room temperature. The seeds were deionised H2O delivered at a rate of 0.5 mL.min . freeze-dried, finely ground (HIL-G-501, Hanil Co., Glucose, fructose, sucrose, and sorbitol (Aldrich Seoul, Korea), passed through a 60-mesh filter, and Chemical Co. Inc., Milwaukee, WI, USA) were used stored at -20°C until further analyses. as the reference sugars for identification, and mannitol (Aldrich Chemical Co. Inc.) was used as an internal Determination of mineral contents standard. A 0.5-g of sample powder was mixed with 15 mL of 65% nitric acid (HNO3). The mixture was diluted Determination of free amino acids with 50 mL of distilled water. An inductively coupled The free amino acids were determined follow- plasma (ICP) emission spectrometer (38 Plus, Jobin ing the method described by Spackman et al. (1958) Yvon, Co., Palaiseau, France) was used to determine with some modifications. One gram of sample powder the essential mineral elements, and an atomic absorp- was hydrolysed with 6 N HCl (10 mL) in a vacu- tion spectrometer (AA-220FS, Varian Spectra, um-sealed ampoule at 110°C for 24 h. The HCl was Han, C. H., et al./IFRJ 27(6) : 1057 - 1066 1059 removed from the hydrolysed sample using a rotary Hydroxyl radical scavenging activity evaporator, and the remaining sample was diluted to The hydroxyl radical scavenging activity a known volume (5 mL) with 0.2 M sodium citrate was measured following a previous method (Chung buffer (pH 2.2). The mixture was passed through a C18 et al., 1997). Hydroxyl radicals were generated by Sep Pak (Waters Co. Milford, USA) cartridge and Fenton reaction in the presence of FeSO4•7H2O filtered through a 0.22 µm membrane filter (Millipore, (Acros Organics, Pittsburgh, PA, USA), that is, 10 Billerica). An automatic amino acid analyser (Bio- mM of EDTA (Sigma Chemical Co., St.